hey Jmac, you know much about TL enclosures? As far as I know, TL boxes are what home audio speaker cabinets are. Are they good for SPL, or would it have to be super huge to achieve it?

paikiah

05-05-2003, 10:36 PM

Originally posted by Jmac
Not a whole lot ... I have no experience in either the design or fabrication of transmission lines ... They're supposed to be pretty hard to get right ...

harder than bandpass?

I heard form someone that loyd's got a TL box that's made for SPL... and I've also heard from elsewhere that a TL box for SPL was HUGE... size of a couch or something...

bigred78797

05-09-2003, 09:56 AM

Yes T-Line boxes can get huge. I built one that was over 100 L or 3&1/2 ft^3 without the port. It was huge but loud. I had my friends at my audio store to test it and it turned out 118.4 db @ 28hz with just one subwoofer in it( a cheap subwoofer at that) . I have one in my truck you can see it on inverted sub post. Usually i can get them tuned lower with a higher spl at the lower frequencies, over sealed or circular ported closures. Typically they are somewhat inefficient though, you can hit high db's at a tuned frequency but once you get out of that frequency range you begin to lose db's... but it's still loud but not as loud. They aren't really that hard to build or design, to me, but they are basically equivalent to the slotted ported boxes you see out there. They also require High excursion subwoofers, preferebly subs with Xlim over 10mm. I destroyed 3 $250 subs before figuring that out.

paikiah

05-09-2003, 10:04 AM

Originally posted by bigred78797
Yes T-Line boxes can get huge. I built one that was over 100 L or 3&1/2 ft^3 without the port. It was huge but loud. I had my friends at my audio store to test it and it turned out 118.4 db @ 28hz with just one subwoofer in it( a cheap subwoofer at that) . I have one in my truck you can see it on inverted sub post. Usually i can get them tuned lower with a higher spl at the lower frequencies, over sealed or circular ported closures. Typically they are somewhat inefficient though, you can hit high db's at a tuned frequency but once you get out of that frequency range you begin to lose db's... but it's still loud but not as loud. They aren't really that hard to build or design, to me, but they are basically equivalent to the slotted ported boxes you see out there. They also require High excursion subwoofers, preferebly subs with Xlim over 10mm. I destroyed 3 $250 subs before figuring that out.

erm, no offense, but I don't think 3 and half cube boxes are what I consider HUGE... when I say huge, I mean double digit figure boxes.118.4dB? Erm, there are people here in the forum who can make that kind of figure with factoryspeakers with hu internal amps (they said it, I haven't seen it myself yet) I mean, I don't know if such a dB figure is gonna impress me. What's the pointof a TL box for SPL, if it can only pump that much?

What you're saying is, TL is no better than a normal ported box in terms of SPL? Howabout SQ?

I'm JUST beginning to learn the fundamentals behind this technology, as well as the cyclone subs...

bigred78797

05-09-2003, 10:18 AM

Yeah you can easily hit 118 db at high frequencies but when you start to go below 50hz or so it becomes harder to reproduce those frequencies. My highs in my truck could probably easily hit 140 db becuase they are reproducing frequencies at around 300+ hz. When you hit low nots like 28 hz it's really hard to hit those with one speaker. As for the size that was just the size of the small enclosure. The entire box ended up being five 1/2 feet tall and 3 ft wide. You also have to keep in mind that i was only using one sub and only pushing 220 watts through it 250 if i was lucky. It's all in the efficiency at that tuning frequency which is the point of SPL. You want your system to be at it's peak efficiency at the tuning frequency or slightly above.

paikiah

05-09-2003, 10:20 AM

Originally posted by bigred78797
Yeah you can easily hit 118 db at high frequencies but when you start to go below 50hz or so it becomes harder to reproduce those frequencies. My highs in my truck could probably easily hit 140 db becuase they are reproducing frequencies at around 300+ hz. When you hit low nots like 28 hz it's really hard to hit those with one speaker. As for the size that was just the size of the small enclosure. The entire box ended up being five 1/2 feet tall and 3 ft wide. You also have to keep in mind that i was only using one sub and only pushing 220 watts through it 250 if i was lucky. It's all in the efficiency at that tuning frequency which is the point of SPL. You want your system to be at it's peak efficiency at the tuning frequency or slightly above.

You mentioned losing dB's with TL boxes... a sharp rolloff like bandpass?

bigred78797

05-09-2003, 10:25 AM

Yep, the spl curve looks more like a jagged mountain rather than a rolling hill with the peak being right above the tuning freq.

bigred78797

05-09-2003, 10:30 AM

This isn't the huge box but this is a smaller version of that box with the same speaker.

paikiah

05-09-2003, 10:33 AM

Originally posted by bigred78797
This isn't the huge box but this is a smaller version of that box with the same speaker.

hmmm, I'm learning something new everyday...

I thought TL enclosures were sealed, and only had these wooden panels to allow soundwaves to bounce off at certain angles...

the cross secional diagrams that I've seen weren't too clear on this anyway.

Hmm, do you happen to have any complex TL box blueprints?

I believe I have seen some posted on the net before, with home made speakers. I didn't see any ports on them, yet the inside was a maze!

bigred78797

05-09-2003, 10:40 AM

Yep here you go, this is the basic cross section of it. im trying to remember the web address, ahh www.t-linespeakers.org they have just about everything you need to know but they don't cover they type of boxes that i build most of theirs are just long ports without a small enclosure on the inside. What ur thinking about i believe is the terminated transmission line. Very complex.

paikiah

05-09-2003, 10:43 AM

Originally posted by bigred78797
Yep here you go, this is the basic cross section of it. im trying to remember the web address, ahh www.t-linespeakers.org they have just about everything you need to know but they don't cover they type of boxes that i build most of theirs are just long ports without a small enclosure on the inside.

I've seen that cross section pic before...and I say that is in effect, a normal vented box.

I was under the impression that TL boxes had weird, irregular ports or walls. Some even look like honrs or something.

bigred78797

05-09-2003, 10:48 AM

Yep that another verson of transmission line boxes. Along with Tapered Quarter Wave-length Transmision line (TQWT) or voagh pipe, and Inverted horns. And to put it simply most slotted ports are versions of transmission lines.

paikiah

05-09-2003, 10:57 AM

Originally posted by bigred78797
Yep that another verson of transmission line boxes. Along with Tapered Quarter Wave-length Transmision line (TQWT) or voagh pipe, and Inverted horns. And to put it simply most slotted ports are versions of transmission lines.

thanks... now you've given me a reason to tell people that I know how to make a TL box. ;) If what you're saying is true, then what i claim would also be tehnically true. ;)

awalbert88

05-09-2003, 12:52 PM

Well, for home theater and home music purposes, you really don't want 140db+ figures. Anything over about 130-135db becomes very overpowering, unless you enjoy listening to movies at Dolby Reference Level (insanely loud). Same for general every day driving with SQ, you don't want the bass to overpower things, you want to not even notice it, because it should blend in perfectly.

Really, really complex TL enclosures can produce very great SPL numbers with very low power and remain extremely clean and crisp. But they also take up as much space as a small car.

bigred78797

05-09-2003, 03:29 PM

Yeah i agree with you... all of that is true. But there are people like me who's main goal in life is to go deaf from something other than an atomic bomb blast. I mainly do this for fun to see how loud i can get a speaker. Now i don't have a setup like that in my home becuase:

#1 i live with my parents
#2 the nieghbors already call the police complaining about noise when im testing my speakers.
#3 i have already gone deaf from listining to my car system

Now with me for everyday driving i just love the bass. sometimes I'll shut off everything above 60 hz and just go on a noise violation rampage, bass is the only reason why i listin to music.